1. Field of the Invention
The present invention relates to devices that are used in conjunction with Magnetic Resonance Imaging (“MRI”) equipment to provide stimuli or entertainment for a patient and to facilitate communication with a patient during an MRI diagnostic treatment or imaging process.
2. Description of the Related Art
MRI has become a preferred technology for generation of high quality images of different tissue types within the human body. Headphone devices to provide auditory stimulation or entertainment for the patient have been developed and improved for use within MRI equipment. The signals that are to be reproduced by the headphones may originate as music or similar entertainment content, communications from the MRI operator to the patient, or patient auditory stimuli used in functional MRI (“fMRI”) and other brain function imaging.
The headphone devices must be able to operate within the MRI environment. The MRI environment typically produces intense magnetic fields and further relies on measurement of small radio-frequency signals created by the response of human tissue to stimulation by radio-frequency signals and other magnetic fields. The MRI environment is also confined by the dimensions of the MRI equipment. More specifically, most MRI equipment includes a bore into which the patient is moved during the imaging operation.
Devices operable to sense sound made by the patient are also implemented in the MRI environment. These devices are generally adapted to allow the patient to communicate with the operator of the MRI equipment and provide a way for the operator to confirm that the patient is relaxed and comfortable. Devices used to receive the sound from the patient must also be compatible with the MRI environment.
The MRI equipment is prone to generating significant amounts of noise during operation. This noise may be created in part by the rapid changes in the current that cause vibration such that knocking can be heard by the patient. The noise generated by MRI equipment is typically loud and is generated across a broad frequency spectrum. Additionally, the noise generated varies in intensity during operation of the MRI equipment. The presence of this noise presents the possibility of injury to the patient's hearing, which has been avoided through use of headphones and/or earplugs.